Ruiz Sibaja, A., and O. Bonilla Manterola. “An Stiffness Coefficients Proposal for Thin Walled Open Beams”. Rev. Téc. Fac. Ing. Univ. Zulia, Vol. 29, no. 3, Nov. 2010, https://produccioncientifica.luz.edu.ve/index.php/tecnica/article/view/6029.